To further the sections studies of mutational events in the mitochondrial genome, we have developed a rapid method of DNA sequencing: by employing the polymerase chin reaction and an amplification primer with a 5' ligand to provide for a simplified method to prepare single stranded DNA, this DNA is easily sequenced by the Sanger technique. This procedure should greatly facilitate the study and diagnosis of human genetic diseases. Progress in adapting RNA:DNA duplexes for the rapid screening of genomic variations: mismatches, substitutions and deletions; has provided some preliminary evidence for heterogenity in the human brain mitochondrial genome. Earlier experiments had suggested that mutations in the mitochondrial genome were very rare events. If the section's preliminary results are confirmed mutational events in the mitochondrial genome may provide some explanation for the pathophysiology associated with certain diseases and aging. Studies of plasm DHEA levels in patients with AIDS and Alzheimer's disease were stimulated by observations that high levels of DHEA may provide protection against viral illness. Plasma DHEA levels were lowered in patients with these two diseases compared to age- matched controls. Investigations of DHEA levels in AIDS and Alzheimers may provide information on whether the lowered levels found in these disease states are specific or merely an indication of disease in general. A double cross-over clinical trial has been initiated to determine whether the administration of DHEA has a beneficial effect in Alzheimer's disease patients.